Twelve-year-old Chico Filippo, whose own donkeys were confiscated years before by the German army, can't stay away from the newly set up American Remount Depot. Here, in the last months of World War II in Italy, thousands of supply mules and donkeys are processed and sent on to the fierce mountain fighting in the Apennines. One of the handlers introduces Chico to a small courageous animal the boy names Sergeant Donkey. Drawn into friendship and then into unexpected danger, Chico must demonstrate his own simple courage.